Automobile and truck wheels include an annular wheel rim capable of receiving and securely holding a pneumatic tire. A wheel disc having a circular configuration is formed within the annular wheel rim. The wheel disc may be solid or may have one or more apertures formed therethrough for aesthetics and to reduce weight. The wheel disc will also of necessity have a plurality of wheel attachment holes formed threrethrough for attachment to the vehicle wheel hub studs.
As is known, vehicle wheels were for many years produced from steel. Such wheels were produced by stamping of the wheel disc and attaching it to a formed rim. However, as technology improved non-ferrous wheels became valuable alternative to the stamped-steel wheels previously known. The fabricating process (forging or casting) allowed the manufacturer to make the wheel wherein the wheel disc has a variety of patterns and configurations. Early wheels were made from steel by casting or forming. While providing improvements over the stamped and formed steel wheel, the wheels made from steel were restricted to the styling design. Eventually because of advancements in fabricating techniques, additional castable or forgeable metal materials were used, including such relatively light-weight materials as aluminum, magnesium, and titanium alloys.
Regardless of the material from which the light metal wheel is formed, the manufacturing process typically results in rough surface, corners, edges and burrs around both the wheel openings and the wheel pockets formed or machined on the face of the wheel. These imperfections must be removed for reasons both of aesthetics and safety. The finishing process which removes rough surface, corners, edges and metal burrs has typically been very time-consuming, involving as is known the use of a variety of grinding, polishing and finishing tools applied with various levels of manual operations and automation. While providing satisfactory results in general, the use of such manpower and equipment has been both time-consuming, quality inconsistent and cost-ineffective, thus being a possible but less-than-optimum solution for the production of wheels on any sort of volume basis. In addition, the use of deburring equipment on light metal wheels, particularly on aluminum alloy wheels, has also been proven to be undesirable because of the tendency for deburring to discolor the metal.
In an effort to overcome the inefficiencies of known methods at wheel finishing, electrochemical finishing of wheels made from a conductive metal have been put forward. The electrochemical process has been used in two ways in which one process relies on an electrochemical reaction between an anode and a cathode and the other process relies on a combination of electrochemistry and mechanical grinding/polishing.
According to the first known technique, the metal part (the anode) is operatively connected with the positive post of a rectifier. The finishing electrode (the cathode) is operatively connected with the negative post of the rectifier. (This arrangement is in opposite order from electroplating.) The finishing electrode is fitted to the metal part to be finished in a spaced-apart relationship. A narrow gap must be maintained between the finishing electrode and the metal part to prevent short-circuiting. An electrolyte is then flowed through the gap formed between the finishing electrode and the metal part. A current is applied such that the current flows from the surface of the anode to the through the electrolyte to the face of the cathode. This flow effects removal of the rough material resulting in a rounded edge and smooth surface.
According to a second known technique, a rotatable grinding wheel, such as an electrically conductive diamond-coated wheel, is provided for deburring. The grinding wheel is charged and acts as a cathode and the metallic, electrically-conductive surface to be ground functions as the anode. In operation, an electrolyte fluid is flowed between the grinding wheel and the sharp edge of the part being worked. Similar to the process mentioned above which relies only on electrochemistry, the mechanical-electrochemical process utilizes a rectifier to provide the desired charges to the anode and cathode.
While the known techniques have provided advancements in the art of finishing parts made from conductive metals, there yet exists opportunities to improve the state of the art. Accordingly, the present invention provides an alternative method of finishing a metallic wheel that is both efficient and cost-effective and provides a further advancement in the state of the art.